Earth and Planetary Astrophysics (astro-ph.EP)

Abstract: The nearby M2 dwarf GJ 3470 has been the target of considerable interest after the discovery of a transiting short-period Neptune-sized planet. Recently, claims regarding the existence of additional transiting planets has gotten some attention, suggesting both the presence of a gas giant in the habitable zone, and that the system hosts a remarkable co-orbital gas giant configuration. We show that the existence of these three additional planets are readily amenable to testing with available data from both ground-based radial velocity data and space-based TESS photometry. A periodogram search of the available radial velocities show no compelling signals at the claimed periods, and the TESS photometry effectively rules out these planets assuming a transiting configuration. While it is doubtlessly possible that additional planets orbit GJ 3470, there is no evidence to date for their existence, and the available data conclusively rule out any planets similar to those considered in this text.

Abstract: The shape of the two gas giants, Jupiter and Saturn, is determined primarily by their rotation rate, and interior density distribution. It is also affected by their zonal winds, causing an anomaly of O(10 km) at low latitudes. However, uncertainties in the observed cloud-level wind and the polar radius, translate to an uncertainty in the shape with the same order of magnitude. The Juno (Jupiter) and Cassini (Saturn) missions gave unprecedented accurate gravity measurements, constraining better the uncertainty in the wind structure. Using an accurate shape calculation, and a joint optimization, given both gravity and radio-occultation measurements, we calculate the possible range of dynamical height for both planets. We find that for Saturn there is an excellent match to the radio-occultation measurements, while at Jupiter such a match is not achieved. This may point to deviations from a barotropic flow above the cloud level, which might be tested with the forthcoming radio-occultation measurements by Juno.